There are certain individuals which are subject to premature labor which can result in either a premature birth or miscarriage. The state of premature labor can be corrected via the use of drugs known as tocolytics and the provision of immediate medical care. However, the premature labor state by and large cannot normally be identified by the patient so as to enable medical help to be sought at the time of such premature labor. The ability of a patient to identify the onset of premature labor and immediately seek medical attention will significantly reduce the instances of premature birth and miscarriage.
Premature birth requires 24-hour per day monitoring of the prematurely born child, at a cost on the order of thousands of dollars per day. Such monitoring usually continues until the child is of sufficient birth weight and sufficiently healthy that he can be discharged, which can require months.
In as many as 45% of the instances of premature birth, silent labor occurs where the onset of dilation, effacement and change in orientation of the cervix occurs without the accompaniment of perceived uterine contractions until perhaps minutes before delivery. Conversely, false labor may occur, including the onset of uterine contractions without dilation or effacement of the cervix.
Further, the ability to determine the extent to which premature labor is occurring can be of immeasurable help to the medical practitioner. The dosage of medication and type of treatment will depend upon the extent to which the premature labor process has progressed. The medication will typically be a tocolytic agent, such as terbutaline, ritodrine, and magnesium sulfate.
Once the cervix has dilated to a dimension in excess of four centimeters, the labor process will have begun in earnest and is not subject to reversal. Therefore the onset of labor must be detected, usually within an hour of its beginning, to have a significant chance of preventing such premature labor.
The use of a pessary has been known for some time. The dictionary definition of pessary is "a device worn in the vagina to support a displaced uterus." A modern day pessary type device is the diaphragm. Diaphragms are typically disks each having a curved continuous edge, typically supported with an internal wire spring.
The current use of a pessary for supporting a displaced uterus has been replaced by surgical procedures.
In other specialized circumstances, a pessary may be prescribed by an obstetrician, such as for the promotion of healing of trophic cervical lacerations, the relief of acute urinary retention due to a retroposition of the uterus in mid-pregnancy, preventing or relieving postpartum subinvolution or retroversion, or to protect against spontaneous abortion in the case of cervical incompetence.
Since the use and utility of the pessary has been proven, and since it lies in a position proximate to the cervical opening, what is needed is a method to use the pessary to indicate the onset of premature labor.
What is needed is a pessary which can be pre-selected to fit different sizes of vaginal canals and cervical sizes, but which does not touch or irritate the cervix or vagina. The pessary should not block the area of the os, and should be made of a material which will not cause a reaction in the vaginal/uterine environment. The device should be smooth, and should be constructed to facilitate insertion and removal.
The methods employed in detecting the onset of premature labor should not register false positive labor indications despite patient movement and normal non-vigorous activities. The needed structure must be available in sterile form and be sterilizable. It should also be amenable to an operating mode which will conserve battery power.